1. Field of Invention
This invention relates generally to an apparatus and method for displaying a map as a navigational aid in a vehicle and, more particular to a method for presenting a map.
2. Description of Prior Art
There is a considerable interest in providing a driver of a motor vehicle with en-route guidance system, usually in the form of computer generated voice messages and/or of real-time maps of the relative vicinity of the motor vehicle.
If in such systems the above mentioned map is used, it is displayed on computer driven screen such as a back-lit LCD or CRT, such screen located somewhere in the dashboard or in the center console as discussed in U.S. Pat. Nos. 4,914,605 and 5,398,188. Also, there are known solutions to displaying any visual information on a "head-up display" where the image is reflected in the vehicle's windshield as discussed in U.S. Pat. Nos. 4,961,625 and 5,422,812 and 5,504,622 or in a separate mirror member as discussed in U.S. Pat. No. 5,469,298 in such a way that the image appears suspended in mid-air in front of the vehicle, with the virtual image focus at or near infinity or practically at infinity.
However, all the prior art display systems fail to allow the driver to obtain all the visual information necessary for successful navigation in a fashion sufficiently fast, easy and intuitive as to limit the distractions to safe level, a level comparable to, for example, glancing into rear-view mirrors or reading traffic and road signs. Instead, they require a substantial mental effort to study and memorize the map presented, and then to mentally correlate the map features with the real landmarks as seen from the moving vehicle. The voice-only systems frequently give the diver commands that are too late to be safely executed or at other times too early to be remembered.